Method of and apparatus for the manufacture of sulphuric anhydride



Dec; 11, 1923. 1,477,107

C. H. CAREY METHOD OF AND APPARATUS FOR THE MANUFACTURE OF SULPHURICANHYDRIDE Filed June 28 1922 Fatented Dec. 11, 1923.

QLAUDE H CAB/EY, OF WILMINGTON, DELAWARE, ASSIGNOR '10 ATLAS POWDER COM-PANY, OF WILMINGTON, DELAWARE. A CQRPORATION OF DELAWARE,

METHOD or AND arrana'rns FOR THE MANUFACTURE or sunrnunrc ANHYDRIDE.

Application filed. June as, 1922. Serial No. 571,489.

T all whom' it may concern:

Be it known that CLAUDE H. CAREY,

in y invention relates to method of and apparatus for the manufacture ofsulphuric anhydride or sulphuric acid by which the contact process maybe carried out with greatly reduced equipment for unit quan- 16 tity ofproduction and greater efficiency may be attained by providing for thesatisfactory conversion of high percentages of SO,

in the gases entering the converter system.

Heretofore contact plants have been oper- 29 ated with percentages of SObelow 9% whereas I propose, by my invention, to use as high as 12% S0from the burningof brimstone in air or 25% from a mixture of 100% S0 gaswith air. It is well-known 25 by those who are familiar with themanufacture of sulphuric anhydride that the difficulty of operating witha high percentage of SO in the gases is the intense heat generated bthe. reacting gases in the converters whic 1prevents the reaction fromgoing to comp etion and causes severe wear on the apparatus. It has beenthe usual practice to use preheaters in advance of the converters and toprovide for the elimination of the heat of reaction by various means,such as radiation from the converter shells or intercoolers'between thesections of the contact material, which involves the use of a heavyinvestment in equipment and of complicated apparatus with greatlyincreased cost both from the.

standpoint of initial installation and of maintainence and operation.

This invention not only allows a very high percentage of SO to becarried in the gas entering the converter system but requires a muchsmaller investment in equipment as will be seen from the accompany-v ingdiagrammaticdrawing, wherein 5 is the main supply pipe to the converterfor cool or partially heated sulphurous acid gas. By

means of a bypass 6 and dampers 30 and 31. of the converter system theincoming gas may be permitted to directly pass into supply pipe 5 or maybe delivered to said pipe nhydride, of which the follow connected to theupper part of the second from a heat exchanger 7 or may be dividedbetween the two. The pipe 5 is in communication through a T 8 with a fancasing, 9, the fan receiving its supply from the T; 8 and dischargingthrough an outlet 10 into the contact compartment 11 of" the converterA.- The contactcompartment 11 is located within a space formed by thewalls 12 and- 13 which lie in spaced relation to the, main wall 14 ofthe contact chamber, so. that"a space 15 is left between thesewwall s'.yvhich space at. the'top is in communicationwith the contactcompartment and at fthe bottom is an communication with' a flue leadingto the T 8. A valve or damper .17 is locatedin the flue 16 for a purposehereinafter set forth. A shell 18 surrounds the wall 14 of theconverter, the space 19 within this shell being in communication with afurnace 20, through a .fiue 21, A waste heat stack 22 leads from theupper part of the space 19, and flue 21 and stack 22 areprovided withcontrolling dampers 23 and 24, respectively. The upper part of the firstconverter A is U0 converter. B by means of a flue 25. .Thedischargefrom. the second converter B into the heat exchanger? isthrough a flue 26 and the ,discharge of the gasses from the heatexchanger is through a pipe 27.

In starting a. converter system it is necessary to bring the catal zerup to a suitable reacting temperature. t is the usual prac 1 ties toaccomplish this by passing hot gases previously heated in a preheaterthrough-the contact chambers. The present process differs from theforegoing by passing the preheating gases from a furnace directly to theconverter shell through the space'19. By recirculating the gasesrepeatedly through the annular space 15, flue 16, T 8 and flue 10 bymeans of the blower or fan 9 the whole apparatus is brought up to thedesired temperature without passing any gas through the completeconverter system. This is especially advantageous when the contact planthas been shut down for a short period and the temperatures in thecontact chambers have dropped to a point unsatisfactory for startingconversion. 108 With this type of apparatus the temperatures may beincreased to the conversion point in contact chamber 11 without losing ahigh percentage of SO, outof the exit stack. Converter B may be broughtup to 110 the desired temperature by gases from convert er A in whichthe major ortion of the SO, has been converted to S It will berecognized by those familiar with the .art of manufacturing sulphuricacid b the contact process that this method of preheating the contactchambers to the proper temperatures is more efiicient and requires amuch smaller investment in equipment than the methods heretoforepracticed. It should be understood that I do not limit the heating ofthe converter shell to furnace gases as any other suitable means may beemployed for thisvpurpose. The contact material to beused in the contactchambers of the converters A and B may be platenized magnesium sulphateas described in U. S. Patents 636,924 and 636,925, although I do wish tolimit myself to this material, or the percentages of platinum containedtherein. The contact material 28 may be distributed in one layer ormore, being supported on suitable screens 29. The fan to be used forrecirculating the gases may be of any standard design used for movinghot gases, or other suitable mechanism may serve the same purpose. It isdesirable to conserve as much heat of the reaction in the converter Aand blower equipment, as possible, by covering the preheating shell andblower connections with some non-heat conducting material. keep the heatradiation from flue 25 and converter B down to the minimum as the gasespassing fromconverter A to B may be at a temperature slightly higherthan desired for entering and passing through I the contact mass inconverter B.

In operation, after the temperature of the converter chamber A has beenbrought up to the desired point, cool,'sulphurous acid gas or gaspartially heated by passing through the heat exchanger 7 passes into T 8where hot gases, in which the major portion of the S0 has been convertedinto 801 are met coming from contact chamber 11 through the space 15 andflue 16. These combined gases pass into the inlet of fan 9 and areforced through flue 10 into contact compartment 11. An approximatelyequal quantity of gas to that flowing through pipe 5 passes out of thecontact chamber into the inlet of converter B through flue 25, where thefinal maximum conversion is obtained. The excess heat of the gases maybe removed by passing thev It is not essential to sired percentage of SOenteringthe contact material may be obtained thereby preventing anappreciable rise in temperature.

This will cause a high percentage of conversion' to take place. I havefound that be, tween 790 and 930 F. the rate of conversion is very rapidand nearly complete for S0 gas concentrations which correspond to aninitial SO content under 13.3% for a gas derived from burning brimstonein air and 28% from mixing 100% S0 gas wlth alr. Enough of the gases aretherefore returned from converter A, after passing through the.

contact mass, to keep the S0 content of the total mixture passing intothe contact mass, such that the temperature rise will not exceed 930 F.While the percentage of SO, in the gas from pipe 5 is being, reduced thegas at the same time is being brought up to the reaction temperature of790 F. A twofold result is, therefore, secured by this method ofoperating. As a result of the conservation of heat in the converterAandits connections, only a small amount of insulating material is neededbetween the outlet of converter A and the contact material in converterB in order to permit the gases to enter the latter at a satisfactorytemperature for conversion.

It is well known that the last 5% to 8% of the total conversion isobtained with difficulty and it is therefore necessary to bring the gasmixtures in contact with the catalyzer at the most favorable temperaturein converter B. As a result of the major part of the S0 having beenconverted into SO,

contact chambers.

It will be appreciated by those familiar with manufacturing sulphuricacid by the contact process one commercial scale that the entire plantinvestment is decreased by operating with a high percentage ofsulphurous acid gas in the system. A high percentage of S0 is desired inthe gas when the plant is manufacturing fuming acid, as the amount of SOabsorbed depends on the amount of SO in the gas, other conditions beingequal.

It must not be understood that I limit my invention to mixtures ofsulphurous acid gas and air as this process would also be applicable toa mixture of sulphurous acid gas and oxygen. I

It is the purpose of my invention to reduce the cost-of manufacturingsulphuric acid by the contact process by reducing the size of theconverter equipment and regulating the temperatures therein so thatcxcessiyo wear on the apparatus is prevented, maximum efiiciency isobtained from the contact material, and a high percentage of sulphurbearing as is carried through the entire contact p ant system, thisreducing the plant investment. I

Having described my invention what I claimis:

1. In apparatus for the manufacture of sulphuric anhydride by thecont-act process, a converter comprising a contact compartment, a supplyconduit for conducting gases to be converted thereto and means forconducting a part of the gases of conversion from said compartment tosaid supply conduit.

2. In apparatus for the manufacture of sulphuric anhydride by thecontact process, a converter comprising a contact compartment, a supplyconduit for conducting gases to be converted thereto and means forconducting a part ofthe gases of conversion from said compartment tosaid supply conduit and means for controlling the extent of dilution ofthe incoming gases by said gases of conversion. V

3. An apparatus for the manufacture of sulphuric anhydride by thecontact process comprising two connected contact chambers, a supplyconduit for-conducting SO to the first contact chamber for conversionand means for conducting a portion of the gases of conversion from thefirst contact chamber to said supply conduit the remainder of the gasesof conversion'passing from the first contact chamber to the secondcontact chamber where conversion is completed.

4. A. structure as recited in cla1m'3 1n combination with means forcontrolling the 6. An improvement in the art of manu facturing sulphuricanhydride by the contact process which consists in introducing adiluting gas from the outlet of a converter containing catalyticmaterialto the sulphurous acid gas and air mixture entering theconverter, thereby reducing the concentration of the reacting gasesentering the contact mass.

7. An improvement in the art of manufacturing sulphuric anhydride by thecontact process which consists in transferrin only a portion of thegases passing through one contact chamber into a second contact chamber,the remainder of the gases reentering the first chamber.

8. An improvement in the art of manufacturing sulphuric anhydride by thecontact process which consists of conducting gases to be converted to acontact chamber and carrying a part of the gases of conversion from saidcontact chamber from an outlet'thereof back to and introducing them intothe stream of incoming gas.

9. An improvement in the art of manufacturing'sulphuric anhydride by thecontact process WlllCh consists of conducting gases to be converted to acontact chamber and carrying a part of the gases of conversion from saidcontact chamber from an outlet thereof back to and introducing them intothe stream of incoming gas in such amount as to prevent a rise oftemperature above 930 F. in the contact chamber.

10. An improvement in the art of manufactoring sulphuric anhydride bythe contact process which consists of conducting gases to be convertedto a contact chamber and carrying a part of the gases of conversion fromsaid contact chamber from an outlet thereof back to and introducing theminto the stream of incoming gas in such amount asto maintain thetemperature in CLAUDE n. CAREY. 1

Witnesses ISAAC Foes, EMMA COLLINS.

